Biophysical Model of Ion Transport across Human Respiratory Epithelia Allows Quantification of Ion Permeabilities

Lung health and normal mucus clearance depend on adequate hydration of airway surfaces. Because transepithelial osmotic gradients drive water flows, sufficient hydration of the airway surface liquid depends on a balance between ion secretion and absorption by respiratory epithelia. In vitro experiments using cultures of primary human nasal epithelia and human bronchial epithelia have established many of the biophysical processes involved in airway surface liquid homeostasis. Most experimental studies, however, have focused on the apical membrane, despite the fact that ion transport across respiratory epithelia involves both cellular and paracellular pathways. In fact, the ion permeabilities of the basolateral membrane and paracellular pathway remain largely unknown. Here we use a biophysical model for water and ion transport to quantify ion permeabilities of all pathways (apical, basolateral, paracellular) in human nasal epithelia cultures using experimental (Ussing Chamber and microelectrode) data reported in the literature. We derive analytical formulas for the steady-state short-circuit current and membrane potential, which are for polarized epithelia the equivalent of the Goldman-Hodgkin-Katz equation for single isolated cells. These relations allow parameter estimation to be performed efficiently. By providing a method to quantify all the ion permeabilities of respiratory epithelia, the model may aid us in understanding the physiology that regulates normal airway surface hydration.     

Seasonal Habitat Use of Agoutis (Dasyprocta azarae) is Driven by the Palm Attalea phalerata in Brazilian Pantanal

Resource availability can influence animal movement causing changes in home‐range size and arrangement between seasons. We investigated the influence of acuri palm (Attalea phalerata) on the occupancy of agouti Dasyprocta azare during both the dry and rainy seasons, as well as the abandonment probabilities in the transition between seasons in the Brazilian Pantanal. The agoutis occupied a high proportion of the forested areas in the rainy season (0.83), but the occupancy decreased in the dry season (0.39). In the rainy season, occupancy by agoutis was not correlated with acuri palm availability, while in the dry season, it was positively correlated with the palm's availability. The acuri palm availability also drove the agoutis' probability of site abandonment from the rainy to the dry season, with higher abandonment probability in sites with low acuri palm availability. These findings show that this large‐seeded palm can be an important resource for the agoutis' populations during the fruit‐scarcity period. The acuri palm seeds may be particularly important for agoutis using fragmented forests, given that the large‐seeded palms are able to persist even in small fragments, which is untrue for other important resource.     

Additive effects of beta-alanine and sodium bicarbonate on upper-body intermittent performance

We examined the isolated and combined effects of beta-alanine (BA) and sodium bicarbonate (SB) on high-intensity intermittent upper-body performance in judo and jiu-jitsu competitors. 37 athletes were assigned to one of four groups: (1) placebo (PL)+PL; (2) BA+PL; (3) PL+SB or (4) BA+SB. BA or dextrose (placebo) (6.4 g day^?1) was ingested for 4 weeks and 500 mg kg^?1 BM of SB or calcium carbonate (placebo) was ingested for 7 days during the 4th week. Before and after 4 weeks of supplementation, the athletes completed four 30-s upper-body Wingate tests, separated by 3 min. Blood lactate was determined at rest, immediately after and 5 min after the 4th exercise bout, with perceived exertion reported immediately after the 4th bout. BA and SB alone increased the total work done in +7 and 8 %, respectively. The co-ingestion resulted in an additive effect (+14 %, p < 0.05 vs. BA and SB alone). BA alone significantly improved mean power in the 2nd and 3rd bouts and tended to improve the 4th bout. SB alone significantly improved mean power in the 4th bout and tended to improve in the 2nd and 3rd bouts. BA+SB enhanced mean power in all four bouts. PL+PL did not elicit any alteration on mean and peak power. Post-exercise blood lactate increased with all treatments except with PL+PL. Only BA+SB resulted in lower ratings of perceived exertion (p = 0.05). Chronic BA and SB supplementation alone equally enhanced high-intensity intermittent upper-body performance in well-trained athletes. Combined BA and SB promoted a clear additive ergogenic effect.     

Carnosine: from exercise performance to health

Carnosine was first discovered in skeletal muscle, where its concentration is higher than in any other tissue. This, along with an understanding of its role as an intracellular pH buffer has made it a dipeptide of interest for the athletic population with its potential to increase high-intensity exercise performance and capacity. The ability to increase muscle carnosine levels via β-alanine supplementation has spawned a new area of research into its use as an ergogenic aid. The current evidence base relating to the use of β-alanine as an ergogenic aid is reviewed here, alongside our current thoughts on the potential mechanism(s) to support any effect. There is also some emerging evidence for a potential therapeutic role for carnosine, with this potential being, at least theoretically, shown in ageing, neurological diseases, diabetes and cancer. The currently available evidence to support this potential therapeutic role is also reviewed here, as are the potential limitations of its use for these purposes, which mainly focusses on issues surrounding carnosine bioavailability.     

Comparing galling insect richness among Neotropical savannas: effects of plant richness, vegetation structure and super-host presence

Plant species diversity maintains the stability of ecosystems and the diversity of consumer species such as insect herbivores. Considering that gall-inducing insects are highly specialized on their host plants and dependent on the occurrence, abundance and distribution of plants, we evaluated the diversity patterns of gall-inducing insect along Brazilian Neotropical savannas and the potential role of plant species richness, vegetation structure and super-host presence on determining these patterns. We found 1,882 individual plants that belonged to 64 different host plant species grouped in 31 families, associated to 112 galling insect species. The galling richness was positively influenced by plant species richness and the presence of the super-host genus Qualea (Vochysiaceae). Plant species richness explained 48 % of the galling richness and areas with presence of super-hosts had more than twice of galling species than areas where they were absent. On the other hand, we found no evidence that larger plants hosted more species of galling insects. We observed that for the diversity of galling insects in the Brazilian Cerrado, vegetation structure explained almost the same portion as plant richness, because structural variables did not have an effect on residuals of galling richness and plant richness regression. Our findings suggests that plant richness has a more important role on the mitigation of natural enemies and adaptive radiation of galling species, while structural aspects of the vegetation does not seem to have that effect. Furthermore, we show that the super-host taxa provide an increment in local galling richness because they present a great diversity of local number of gall morphospecies (i.e. alpha diversity) and the high turnover of morphospecies among different localities (i.e. beta diversity). Therefore we argue that the quality of resources (richness and super host presence) appears to be a most important factor for the diversity of galling insects in Neotropical systems, than the amount of resources.     

Structure of a mosaic hybrid zone between the field crickets Gryllus firmus and G. pennsylvanicus

Hybrid zones provide insight into the nature of species boundaries and the evolution of barriers to gene exchange. Characterizing multiple regions within hybrid zones is essential for understanding both their history and current dynamics. Here, we describe a previously uncharacterized region of a well‐studied hybrid zone between two species of field crickets, Gryllus pennsylvanicus and G. firmus. We use a combination of mitochondrial DNA sequencing, morphological data, and modeling of environmental variables to identify the ecological factors structuring the hybrid zone and define patterns of hybridization and introgression. We find an association between species distribution and natural habitat; Gryllus pennsylvanicus occupies natural habitat along forest edges and natural clearings, whereas G. firmus occupies more disturbed areas in agricultural and suburban environments. Hybridization and introgression occur across patch boundaries; there is evidence of substantial admixture both in morphological characters and mtDNA, over a broad geographic area. Nonetheless, the distribution of morphological types is bimodal. Given that F₁ hybrids are viable and fertile in the lab, this suggests that strong pre‐zygotic barriers are operating in this portion of the hybrid zone.     

Acoustic detection of cell adhesion to a coated quartz crystal microbalance – implications for studying the biocompatibility of polymers

Biocompatibility of polymers is an important parameter for the successful application of polymers in tissue engineering. In this work, quartz crystal microbalance (QCM) devices were used to follow the adhesion of NIH 3T3 fibroblasts to QCM surfaces modified with fibronectin (FN) and poly-D -lysine (PDL). The variations in sensor resonant frequency (Δf) and motional resistance (ΔR), monitored as the sensor signal, revealed that cell adhesion was favored in the PDL-coated QCMs. Fluorescence microscopy images of seeded cells showed more highly spread cells on the PDL substrate, which is consistent with the results of the QCM signals. The sensor signal was shown to be sensitive to extracellular matrix (ECM)-binding motifs. Ethylenediaminetetraacetic acid (EDTA) and soluble Gly-Arg-Gly-Asp-Ser (GRGDS) peptides were used to interfere with cell-ECM binding motifs onto FN-coated QCMs. The acquired acoustic signals successfully showed that in the presence of 30 mM EDTA or 1 mM GRGDS, cell adhesion is almost completely abolished due to the inhibition/blocking of integrin function by these compounds. The results presented here demonstrate the potential of the QCM sensor to study cell adhesion, to monitor the biocompatibility of polymers and materials, and to assess the effect of adhesion modulators. QCM sensors have great potential in tissue engineering applications, as QCM sensors are able to analyze the biocompatibility of surfaces and it has the added advantage of being able to evaluate, in situ and in real time, the effect of specific drugs/treatments on cells.     

The extent of whole‐genome copy number alterations predicts aggressive features in primary melanomas

Recent evidence indicates that melanoma comprises distinct types of tumors and suggests that specific morphological features may help predict its clinical behavior. Using a SNP‐array approach, we quantified chromosomal copy number alterations (CNA) across the whole genome in 41 primary melanomas and found a high degree of heterogeneity in their genomic asset. Association analysis correlating the number and relative length of CNA with clinical, morphological, and dermoscopic attributes of melanoma revealed that features of aggressiveness were strongly linked to the overall amount of genomic damage. Furthermore, we observed that melanoma progression and survival were mainly affected by a low number of large chromosome losses and a high number of small gains. We identified the alterations most frequently associated with aggressive melanoma, and by integrating our data with publicly available gene expression profiles, we identified five genes which expression was found to be necessary for melanoma cells proliferation. In conclusion, this work provides new evidence that the phenotypic heterogeneity of melanoma reflects a parallel genetic diversity and lays the basis to define novel strategies for a more precise prognostic stratification of patients.